Genetic analysis of genealogies in mentally retarded autistic probands from Saguenay Lac-Saint-Jean (Quebec, Canada).

Autism is a heterogeneous disorder for which we have evidence of both genetic and environmental determination. The genealogies of 16 autistic probands born in Saguenay Lac-Saint Jean were reconstructed and compared to those of 48 matched control individuals distributed in three different groups. The mean inbreeding and kinship coefficients were calculated. Both coefficients were not found to be increased in the autistic group compared to the control groups. These findings support the conclusions reached by Jorde et al. (1990) which indicated that a single gene was unlikely to account for most cases of autism.